: Artistically I'm going to take a few examples
: 1:Star Trek, does any of the episodes (series') made
: after Gene Rodenberry's death make those episodes any
: less Star Trek.
No, but the original Star Trek did not build nearly as expansive a universe outside the immediate events as Myth did. The later Treks did start building such a universe... and have since contradicted themselves many times. Of course every time someone goes back in time in Star Trek, the whole universe changes... which is why we never had the Eugenics Wars in 1996, and thus Star Treks 2-6 never happened.
: 2.Star Wars the Empire strikes back was not totally
: written by Lucas, it mainly written by someone else.
But it was supervised and approved by Lucas, and is thus cannon.
: 3.The massive History of MiddleEarth books written by
: Christopher Tolkien, are the any less Lord of the
: Rings Canon.
The History of Middle Earth books are almost entirely compilations, crossreferences, and analysis of JRR's original notes (he wrote a LOT of stuff that he never published), mixed in with the original books. Same goes for all of the Lost Tales books, and even the Silmarillion, which I doubt anyone would question the authority of.
: Perhaps this is what Bunige intended all along (Okay
: thats really far fetched but hey) They had acces to
: bungie concept work, they may have changed it less
: than you think.
Most of the "new" information in M3 (and other new MJ-Mythverse info that wasn't mentioned in M3), was made up by MJ. Bungie didn't leave them a lot of "concept work" to work with.